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  1. import java.util.function.Function;
  2.  
  3. interface Monad<T> {
  4. 	public <U> Monad<U> bind(Function<T, Monad<U>> f);
  5. }
  6.  
  7. class Maybe<T> implements Monad<T> {
  8. 	public Maybe(T val) {
  9. 		this.val = val;
  10. 	}
  11.  
  12. 	public T getVal() {
  13. 		return val;
  14. 	}
  15.  
  16. 	@Override
  17. 	public <U> Monad<U> bind(Function<T, Monad<U>> f) {
  18. 		if (val == null)
  19. 			return new Maybe<U>(null);
  20. 		return f.apply(val);
  21. 	}
  22.  
  23. 	private final T val;
  24. }
  25.  
  26. public class MonadApp {
  27. 	public static void main(String[] args) {
  28. 		Maybe<Integer> x = new Maybe<>(5);
  29. 		Monad<Integer> y = x.bind(v -> new Maybe<Integer>(v+1))
  30. 		                    .bind(v -> new Maybe<Integer>(v*2));
  31. 		System.out.println( ((Maybe<Integer>)y).getVal() );
  32. 	}
  33. }
Compilation error #stdin compilation error #stdout 0s 0KB
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stdin
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Standard input is empty
compilation info 
Main.java:26: error: class MonadApp is public, should be declared in a file named MonadApp.java
public class MonadApp {
       ^
1 error
stdout
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Standard output is empty
https://ideone.com/S4UO0N
language:
Java (HotSpot 12)
created:
5 years ago
visibility:
public

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